IlvPathSteppingData Class Reference

Graphic path-related class. More...

#include <ilviews/graphics/path.h>

Inheritance diagram for IlvPathSteppingData:

List of all members.

Public Member Functions
IlFloat	getAngle () const
	Gets the angle of the current step.
IlUInt	getCurPath () const
	Gets the current path.
const IlvPoint *	getCurPosition () const
	Gets the coordinates of a point on the current segment.
IlUInt	getCurSegment () const
	Gets the current segment in the current path.
const IlvGraphicPath *	getGraphicPath () const
	Gets the graphic path.
const IlvPointArray *	getTransformedPaths () const
	Gets an array of transformed IlvPointArray.
const IlvTransformer *	getTransformer () const
	Gets the current transformer.
IlAny	getUserArg () const
	Gets the user-defined value given to the constructor.
IlUInt	getUserStep () const
	Gets the step used in stepping.
virtual void	init (const IlvGraphicPath *gp, const IlvPointArray *transformed, const IlvTransformer *tr)
	Reinitializes the drawing data.
virtual void	stepping ()
	Implements the algorithm to travel along the graphic path.
Protected Member Functions
	IlvPathSteppingData (IlUInt userStep, IlAny userArg)
	Constructor.
virtual IlBoolean	acceptPath ()
	Protected Member Function.
virtual IlBoolean	beginStepping ()
	Begins the travelling operation.
virtual IlBoolean	doIt ()=0
	Protected Member Function.
virtual void	endStepping ()
	Begins the travelling operation.

---

Detailed Description

Graphic path-related class.

Library: views

The IlvPathSteppingData class is an abstract class. Instances of this class are intended to be associated with an IlvGraphicPath object. Its main purpose is to travel the collection of polypoints, considered for this purpose as polylines, and to call its member function doIt periodically. How often doIt is called depends on the step of the IlvPathSteppingData.

The step is not time-based but must be considered as a distance along the path.

See also:

IlvGraphicPath, IlvPathDrawingData.

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Constructor & Destructor Documentation

IlvPathSteppingData::IlvPathSteppingData	(	IlUInt	userStep,
		IlAny	userArg
	)			[protected]

Constructor.

The constructor initializes a new IlvPathSteppingData object with a stepping distance of userStep and a user parameter of userArg.

Parameters:

	userStep	The stepping distance.
	userArg	The user parameter.

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Member Function Documentation

virtual IlBoolean IlvPathSteppingData::acceptPath

(

)

[protected, virtual]

Protected Member Function.

Called by stepping before processing a new point array. If it returns IlFalse, this point array is ignored and stepping proceeds with the next one. The default implementation does nothing and returns IlTrue. This method is called by the method stepping and is meant to be redefined in subclasses. The default implementation is minimal.

virtual IlBoolean IlvPathSteppingData::beginStepping

(

)

[protected, virtual]

Begins the travelling operation.

Called by stepping before anything else. If it returns IlFalse, stepping returns immediately without calling endStepping. The default implementation does nothing and returns IlTrue. This method is called by the method stepping and is meant to be redefined in subclasses. The default implementation is minimal.

virtual IlBoolean IlvPathSteppingData::doIt

(

)

[protected, pure virtual]

Protected Member Function.

Called at each step by stepping. If it returns IlFalse, stepping returns immediately without calling endStepping. This method is called by the method stepping and is meant to be redefined in subclasses.

Implemented in IlvPathDrawingData.

virtual void IlvPathSteppingData::endStepping

(

)

[protected, virtual]

Begins the travelling operation.

Called at each step by stepping. The default implementation does nothing. This method is called by the method stepping and is meant to be redefined in subclasses.

IlFloat IlvPathSteppingData::getAngle

(

)

const

Gets the angle of the current step.

Holds the angle of the current step relative to a horizontal line. This value is not always equal to the angle of the current polyline segment. This method is called by the method stepping and is meant to be redefined in subclasses. The default implementation is minimal.

IlUInt IlvPathSteppingData::getCurPath

(

)

const

Gets the current path.

Holds the index of the current IlvPointArray.

const IlvPoint* IlvPathSteppingData::getCurPosition

(

)

const

Gets the coordinates of a point on the current segment.

Holds the actual coordinates of a point on the current segment. This point is the origin of the current step.

IlUInt IlvPathSteppingData::getCurSegment

(

)

const

Gets the current segment in the current path.

Holds the index of the current segment in the current path, that is, the index of the last IlvPoint crossed in the current IlvPointArray indicated by _curPath.

const IlvGraphicPath* IlvPathSteppingData::getGraphicPath

(

)

const

Gets the graphic path.

Returns the graphic path. This is set each time init is called.

Returns:

The graphic path.

const IlvPointArray* IlvPathSteppingData::getTransformedPaths

(

)

const

Gets an array of transformed IlvPointArray.

Returns an array of transformed IlvPointArray. The member function stepping uses this array instead of the points contained in the IlvGraphicPath (these two data items may be identical if the transformer returned by getTransformer is 0).

Returns:

An array of transformed IlvPointArray.

const IlvTransformer* IlvPathSteppingData::getTransformer

(

)

const

Gets the current transformer.

Returns:

The current transformer.

IlAny IlvPathSteppingData::getUserArg

(

)

const

Gets the user-defined value given to the constructor.

Returns the user-defined value given to the constructor.

Returns:

The user-defined value given to the constructor.

IlUInt IlvPathSteppingData::getUserStep

(

)

const

Gets the step used in stepping.

Returns the step used in stepping.

Returns:

The step used in stepping.

virtual void IlvPathSteppingData::init	(	const IlvGraphicPath *	gp,
		const IlvPointArray *	transformed,
		const IlvTransformer *	tr
	)			[virtual]

Reinitializes the drawing data.

Reinitializes the drawing data between subsequent calls to stepping. transformed is an array of IlvPointArray. It contains the points of the IlvGraphicPath, and the transformer tr has been applied to each of them. stepping uses this data instead of the original points of gp. If tr is 0, transformed may be equal to the internal array of the graphic path, that is, gp->getPaths().

Parameters:

	gp	The graphic path.
	transformed	The array of transformed IlvPointArray.
	tr	The transformer to be applied to gp.

virtual void IlvPathSteppingData::stepping

(

)

[virtual]

Implements the algorithm to travel along the graphic path.

Implements the algorithm to travel along the graphic path and calls doIt every time a distance equal to the step is travelled. In other words, stepping approximates each polypoint of the IlvGraphicPath by a polyline whose segments all have the same length, step. For each one of these segments, stepping calls doIt.

stepping calls several virtual methods to allow subclasses to perform specific actions without rewriting the entire stepping algorithm.

• Before doing anything else, stepping calls beginStepping. If it returns IlFalse, the method returns immediately (without calling endStepping).
• The algorithm basically consists of two nested loops, the first one on the point arrays polyline and the second one on the points of a point array. Before starting a new point array, stepping calls acceptPath: if the return value is IlFalse, the point array is ignored and the next one is picked.
• doIt is called at each step, as described above. If it returns IlFalse, stepping returns immediately (without calling endStepping).
• When all the polypoints have been processed, endStepping is called.

This method is responsible for updating most of the protected fields returned by the following get methods.